Process for the manufacture of adsorbent clay



' April 1931- 'r. HENDERSON ETAL I 7 PRQCESS FOR THE MANUFACTURE OF ADSORBENT CLAY Filed May 29. 1928' 2 Sheets-Sheet 1 W I 4 v E r7 T7'O/QNEW April 14, 1931. T. HENDERSON ET AL 1,800,687

PROCESS FOR THE MANUFACTURE OF ADSORBENT CLAY Filed May 29, 1928 2 ShetSf-Sheet 2 Wafer I fic/a 7Z7m. 7 4.

Pa/p Prehcafer Packer 4 7 foe/v5 K 1 Patented Apr. 14,1931

UNITED STATES PATENT OFFICE THOMAS L. HENDERSON AND WILLIAM KELLEY, OF LOS ANGELES, CALIFORNIA, AS- SIGNORS, BY MESNE ASSIGNMENTS, TO FILTROL COMPANY OF CALIFORNIA, A COR- PORATION OF CALIFORNIA PROCESS FOR THE MANUFACTURE OF ADSORBENT CLAY Application filed May 29, 1928. Serial No. 281,559.

This invention relates to a process for the manufacture of adsorbent clay capable of bleaching vegetable, animal, or mineral oils, waxes, or greases.

One object of the invention is the provision of a process in which the final acidity of the clay may be very accurately controlled.

Another object is to make it possible to manufacture the maximum amount of high grade adsorbent clay by the use of a given quantity of acid.

Another object is to make it possible to manufacture a high gradeadsorbent from a crude clay otherwise not commercially feasible to use.

Other objects will be apparent from the following description.

Referring now to the drawings,

Fig. 1 illustrates in side elevation and more or less diagrammatically, the assemblage of apparatus which we prefer to use in carrying out our process.

Fig- 2 is a flow sheet illustrating the process.

In Fig. 1, numeral 1 indicates a three compartment bin, holding a different kind of clay in each compartment. Beneath the bin is a treating tank 2 which may be provided with an agitator 3 and means for driving same. Means for transferring the clay to the treating tank are provided; also means for filling the tank with water and acid.

The treating tank is arranged to empty into a sump tank 4 on a still lower level. The capacity of this tank is preferably several times that of the treating tank. The sump tank serves the purpose of blending chargesfrom the treating tank to insure a uniform product.

A pump 5 serves to transfer the mud from the sump tanks to a pulp storage ,tank 6 located on a higher level, from'which a battery of centrifuges 7 may be supplied by gravity.

There are preferably four batteries of'centrifuges altogether, arranged tierwise as shown, and having a battery'of wash tanks 8 between the centrifuges. From the pulp storage tank',therefore, the clay may be run into the centrifuges, there freed from liquid, run

into the washing tanks by gravity, .washed, centrifuged once more in a lower battery of centrifuges, washed again, and so on as many times as necessary.

Beyond the last centrifuges is a hopper 9, arranged to receive dry clay from the chute 12 and to feed it by gravity to the head of an inclined kiln 10. This kiln, which is of the rotary type, serves as a preheater for a mixture of wet and dry clay, preliminary to the actual drying operation, which occurs in a drier or kiln mill 11.

From the kill mill (Raymond type or its permissible substitute, a kiln drier of the Ruggles-Coles type) there is a return pipe 12 for a portion of the dry and pulverized clay to the entrance of the preheating kiln. The purpose of such return will be later explained.

A fine grinding mill 13 and a packing hopper 14, with the conventional conveying means therebetween, complete the apparatus assembly.

In the process which we have invented, we use three kinds of clays, which we designate A, B, and C, respectively.

A is a bentonitic clay found near Chambers, Arizona, and has little decolorizing efficiency before being treated. I

B is a clay high in silica and low in alumina and carbonates, being a siliceous volcanic clay and is found in the Mojave Desert and near Tehachapi, California. It has considerable decolorizing efiiciency before being activated and consequently does not require as much acid to activate it as clay A.

Clay C is any highly basic clay rich in carbonates, particularly in magnesium carbonate or in aluminum hydrate or other bases, and low in or free from bases forming insoluble sulfates. Such clays are found in- Death Valley and elsewhere in California.

It might be inquired as to why the entire product is not made from clay B since this clay requires less acid to activate it than does clay A. The reason is that the use of the combination of clays produces an ultimate product of higher adsorptive eflicien'cy and olfthe average just passing 60, is the treating tank.

preferred size for the raw crushed clay.

The acid treatment of the clay is carried out so that at the end of the-treatment of a batch in the treating tank, there have been added 2000 pounds of clay (dry weight).

Approximately 65% of the batch weight of clayA is first charged into the treating tank. A weight of water equal to that of the clay A (1300 lbs.) is now added and then an amount of 66 Baum sulfuric acid equal of clay, or 250 pounds. The charge is now heated by the injection of steam to a minimum of about 214 -F., which entails placingv about 10 pounds per square inch steam pressure upon the charge. The steam may be the sole agitating means or a mechanical or air agitator may be used in addition. Boiling Without pressure may also be practiced.

After an interval of about 1 hours, a fortifying charge of acid of 150 lbs. (W/ of the total charge of clay) is run into the At the end of 3 hours the clay will be found to be completely disintegrated and the acidity to have dropped to between 5% and 10%. H SO Another 'fortifying charge of 100 lbs. (5% of the total charge of clay) of acid is thereupon added,'followed immediately by a charge of 600 lbs. (30%) of clay B.

This clay upon its introduction meets a considerably lower acidity in the treating tank than did clay A. Nevertheless vthe lower.

acidity is still ample to activate clay B because that material already possesses considerable decolorizing-power in its raw state. Another hours heating at about 212 to 214 F. with or without pressure is now given 7 to the batch. The acidity drops, during that. time, from about 10% or 15% to about 2%,

whi his approximately an equilibrium figure. Even prolonged boiling would not serve to lower it very materially. The problem is now how to get rid of this residual acidity without using expensive chemicals. This condition has been met by the use of the basic clay,which not only acts as a neutralizer, but adds'a component of some value to i as ' The treated charge of clay is now dropped to the sump tank 4 where it may be blended the product. In other words, some slight activation of clay C does occur. The addition of about 100 lbs. of clay G at this point, therefore, accomplishes these results.

with charges treated in other tanks or at other times in the same tank. T 1

The contents of the sump tank are elevated to the pulp storage tank 6. The pulp is from there fed by gravityto the first tier of centrifuges and given its first wringing whilej hot. The clay-is then conveyed into the wash tanks located, on the next lower about the sameconsistency that it had been. Hot soft water is used forwashing purposes. Since the object of the washing process is to get rid of free acid and soluble salts, particularly sulfates, andthese are much more soluble in hot water than cold, and in soft water than hard, the importance of heat and softness is apparent- Three washings and four wringings are therefore preferably given the product, and at the end of that treatment it contains substantially no free sul- I furic acid and no soluble sulfates. to approximately 12 /2% of the total charge The clay is now moist but not wet and very cohesiv From the last centrifuges it is delivered to the preheating kiln 10. Thev kiln is not intended to be a final drier, but serves as a preheater for a mixture of dry clay from the hopper 9, and moist clay from the last the rotating kiln, it was found that there was a great-tendency for the clay to form into balls, sometimes of considerable size. Escape of moisture from the interior of these balls was very diflicult, so drying was hindered.

The difficulty was,overcome in a unique manner, namely by inixing the moist clay before its entry into: the preheater with a maximum of about 50% by weight of dry powdered clay. Forthis purpose a pipe 12 is provided, the function of which is to return a part of the output of the drier or kiln mill 11 back to the hopper 9' and thence to the entrance to the preheater. The'mixing of the dry"-claywith'themoist' is accomplished by the motion of the rotary kiln and also by an interior conveying screw with which the kilnmay be provided- By such procedure the ball formation is practically entirely eliminated.

After leavingthe preheater, the clay is conveyed as rapidly as possible to a kiln mill 11' of the Raymond type, or to a rotary drier of the Ruggles-Coles type, or any indirect heat rotary kiln. Such machines are well known in the art and need no further description. 'After leaving the mill 11, the clay is ground, whereby most of it is reduced to a size finer than 200 mesh. It is now ready for bagging and shipment for use.

While we have in the foregoing described the process which weprefer to use, it should be understood that it is capable of many modifications without departing from the spirit of the inventioii. 'Some of them will bespecifically mentioned hereinafter, but

others will be apparent to those skilled in the art.

Hydrochloric acid may be used in lace of sulfuric. A twoclay process may e used in place of a three-clay process if a material having some activity and considerable basicity is at hand for use as a B clay. The proportions of clay and acid, time and temperature of treatment may be varied to' suit the requirements of different clays inways in which chemists are able to determine. Widely different apparatus may be used to carry out my process. The product itself can be, and is varied, to suit the use to which it is put. For'instance, it has been found that mineral oils are more susceptible to decolorization by a slightly acid clay. In the manufacture for this use, therefore, only such an amount of clay C is used as determined .by analysis Will leave a slight acidity U ness to clay, the steps which comprise activating an initially nearly inert clay with a dilute mineral acid until the acidity of said acid is substantially lowered, then adding another clay having some initial activity to the mixture of the first clay and acid and then activating the mixed clays. i

2. In the process of imparting adsorptiveness to clay, the steps which comprise activating an initially nearly inert clay with a dilute mineral acid, adding to the said mix ture of acid and clay a second initially active clay to bemade more active by the remaining acidity and then adding a third basic clay to substantially neutralize the acidity of the mixture.

3. In the process of imparting adsorptiveness to clay, the steps whi h comprise activating an'initiall nearl ert clay with a dilute mineral aci adding to said mixture of acid and clay a second initially active clay to be made more active by the remaining acidity, then adding a third basic clay to substantially neutralize the acidity of the mixture and then removing all water-soluble substances from the product.

4. In the process of. activating clay the steps which comprise heating an initially nearly inactive clay with about 25% sulfuric acid and adding a second initially active clay when the acidity has been reduced to between 5% and 10%, again heating and adding a third basic clay when the acidity has been reduced to about 2%,

5. A process according to claim 4 in which the first nearly inactive clay is of the bentonite type found near Chambers, Arizona, the second, an active siliceous volcanic clay, and the third clay, one high in basic substances which form soluble sulfates.

6. The process of activating clay which comprises heating together to about 214 F. for about three hours a mixture of clay, water, and acid in the following ratio: 1300 lbs. of clay possessing little initial activity, 1300 lbs/of water, and 250 lbs. of 66 Be. H2804; then adding 150 lbs. of 66 B. H SO and 600 lbs. of a clay having some initial activity and being low in alumina and carbonates; heating to about 214 for approximatelyanother hour; then adding enough. of a basic clay suflicient to substantially neutralize the remaining acidity of the batch; and then removing water soluble substances from the clay.

7. In the process of activating clay, the steps which comprise treating the clay with acid, removing water soluble substances, mixing the moist clay with a substantial propor- 3 tion of dry activated clay and then drying the mixture.

8. The process of drying clay which comprises mixing with the wet clay a substantial proportion of dry clay and then drying the mixture.

9. The process of preventing the balling of clay while drying same, which comprises with the moist clay a substantial proportion of dry clay and then heating the mixture while subjecting it to a rotary motion.

10. An activated clay possessing an acidity, due to free H SO of less than 0.50% but more til-Zn 0.10%.dd d1 11. activate ay pomessing an aci 'ty due to free H SO of about 0.25% by weight.

. In testimony whereof, we have hereunto set ourhands at Los Angeles, California, this 22'day of May, 1928.

THOMAS L. HENDERSON. WILLIAM KELLEY. V 

